In many surgical procedures, it is often necessary to ligate a plurality of vessels within the surgical site. The vessels may be severed downstream of the ligated portion. In some instances, a vessel may be ligated in spaced apart areas and the portion of the vessel between the ligations removed. The purpose of ligating vessels is to maintain the surgical site free from an excess of blood and reduce blood loss in the patient. Also in some surgical procedures where tumors and the like are to be removed, the tumor or organ may have to be separated from said vessels. Before separating, the vessels are ligated. Once a blood vessel is completely shut off, hemostatis, that is, the natural closing of the end of the vessel so as to stop blood flow, will occur within several days time depending on the vessel. The body in the meantime will continue to allow blood flow around the ligated area through appropriate capillaries and secondary vessels with the natural psysiological function of the body enlarging these bypass vessels until adequate blood flow is obtained. Hence, when ligating the vessel there should be positive stoppage of the blood flow in the main vessel. Failure to provide complete stoppage may cause blood loss in the patient and may also disrupt the natural hemostatis and concurrent manufacture of new paths of blood flow in the patient.
In the past, the closing of the vessel was usually accomplished using ligatures; that is, filaments or threads which the doctor tied around the vessel to be closed. This is a time-consuming process and one where positive closure of the vessel is not always accomplished. In recent years hemostatic clips have been replaced by ligatures in surgical procedures to close blood vessels and other ovaducts. Very often these hemostatic clips are narrow U or V shaped strips formed of tantalum or stainless steel which are capable of being deformed and possess sufficient strength to retain the deformation while clamped about a blood vessel. Even more recently, hemostatic clips made from biocompatible polymer materials which are either absorbable or non-absorbable in body tissue have been used to ligate vessels. Examples of such polymeric hemostatic clips are disclosed in copending commonly assigned patent application Ser. Nos. 276,131 filed June 22, 1981, and 282,165 filed July 31, 1981.
In most instances, the hemostatic clip should positively close the vessel and stop the flow of blood. The clip should be sufficiently tight about the vessel so that when the surgeon is working in the cavity or area where the vessels have been ligated, the surgeon will not inadvertently remove or disrupt a hemostatic clip either with a sponge or movement of an instrument or the like. The clip should have simple, smooth lines to reduce possible trauma and make the clip relatively easy to manufacture.
What we have discovered is an improved ligating clip structure which, when placed about a vessel, closes the vessel and positively locks the vessel closed. Our new improved hemostatic clip locks tighter to the vessel the larger the vessel and the more pressure placed on the clip by the blood trying to flow through the vessel. Our clip once locked in place is not inadvertently removed or unlocked by being jostled. Our new improved hemostatic clip has simple, smooth lines and is easy to manufacture.